The railroad industry employs a variety of railroad cars for transporting products. Many of these cars, such as boxcars or auto rack railroad cars, are enclosed to protect the products or vehicles being transported. The enclosed railroad cars generally include one or more sliding doors to provide access to the interior of the cars. The doors are generally mounted on upper and lower tracks which are attached to the frames of the cars. As described in more detail below in relation to auto rack railroad cars, the guide brackets attached to the lower end of the door and the lower tracks tend to wear out the tracks. Currently, there is no guide bracket for a lower door track which reduces or eliminates this wear on the guide bracket or the tracks.
Auto rack railroad cars which transport newly manufactured vehicles including automobiles, vans and trucks, provide a prime example of this wear problem. Auto rack railroad cars, known in the railroad industry as auto rack cars, often travel thousands of miles through varying terrain. The typical auto rack car is compartmented, having two or three floors, a frame, two side walls, a roof and a pair of doors at each end of the car. The doors protect the auto rack car from illegal or unauthorized entry to prevent theft or vandalism of the vehicles. The doors also prevent flying objects from entering the car and damaging the vehicles. The doors can be unlocked and easily and quickly moved between closed and open positions to provide access to the vehicles in the auto rack car.
Examples of such doors for auto rack cars are generally illustrated in U.S. Pat. Nos. 3,995,563, 4,077,330 and 4,917,021. The bottom of each door includes at least two guide brackets with roller assemblies attached thereto. Each roller assembly includes a roller which engages the horizontally disposed bearing member of the lower door track attached to the frame of the auto rack car to facilitate movement of the door along the track. The guide bracket includes a hook which engages the inner surface of the vertically disposed guide member of the lower door track to prevent the door from falling off the track. The guide bracket and the track are both made of a suitable metal such as steel.
When the door is moved between open and closed position, the hook engages and slides along the inner surface of the guide member, thereby guiding the movement of the door on the track. This metal-on-metal contact causes substantial wear on the inner surface of the guide member and on the guide bracket. Additionally, when the auto rack car is attached to a train, the normal movement of the train on rails along flat surfaces causes the door to vibrate. This vibration causes the hook to continuously engage the inner surface of the guide member and results in further wear on the guide member and on the guide bracket. The wear on the guide member and on the guide bracket is exponentially increased as the auto rack car travels at high speeds and through varying terrain. The bottom of the doors on many auto rack cars also tend to lean outwardly from the frame. This increases the force of the engagement between the hook and the inner surface of the guide member and therefore causes further wear on the guide member and on the guide bracket. On many auto rack cars, the hook wears the guide member razor thin or completely wears out the guide member. In some auto rack cars, the worn guide member creates a pocket in which the hook rests which thereby prevents movement of the door. In such cases, the door must be physically moved inwardly, disengaging the hook from the pocket before moving the door. This makes the door more difficult to open. Although grease may be applied to the guide member to reduce this wear problem, grease is rarely used or correctly applied in the field.
When the guide member is worn sufficiently thin or completely worn out, the door and specifically the rollers may come off the track. Because this presents a potential safety hazard, the guide member or the entire lower door track must be repaired before the guide member is worn away. To replace the guide member or lower door track, the guide member or the entire track must be cut off the frame (i.e., using a torch) and a new guide member or lower door track must be attached (i.e., welded) to the frame of the auto rack car. This repair of the worn guide members on an auto rack car which includes four tracks (i.e., one for each door) is relatively expensive. The worn guide brackets also need to be replaced in some instances. Moreover, revenue may be lost from having the auto rack car out of service to repair the tracks.
U.S. Pat. No. 4,917,021 discloses door finger guides for doors on auto rack cars which guide the upper ends of the doors and prevent wear along the upper door tracks when the doors are opened and closed. However, U.S. Pat. No. 4,917,021 does not suggest any guide bracket or wear member for the lower door track. Further, there is no known commercially available product or other known device or apparatus which prevents the wear problem of the guide bracket and the guide member of the lower door track of auto rack cars, of box cars, or of other enclosed railroad cars.